There is now in extensive use a three-conductor electrical cable that includes a pair of insulating wires for conducting alternating current and a centrally disposed non-insulated ground wire, all being encapsulated by an insulating sheath. The outer insulating sheath in which the three wires are disposed in parallel relation in a common plane generally presents a substantially oval shape in cross-section, being substantially flat on the elongate sides thereof.
Electrical receptacles for employing such a three-conductor cable without severing the conductors are known in the art, such a receptacle being shown and described in U.S. Pat. No. 3,966,152 issued to Menasche Bromberg on June 29, 1976 and assigned to the same assignee as the present invention. Preparation of cable for use in such a receptacle is achieved by making a pair of elongate slits through the outer insulating sheath on each side of the ground wire and generally between the ground wire and each adjacent insulated conductive wire. The slitting is done carefully so that the insulation on the outside conductive wires is not damaged. Prior to installation of the slit cable into the receptacle, the insulated outer conductive wires are bowed or spread outwardly from the central ground wire for being received by the receptacle that contains insulation piercing contact elements arranged to penetrate the insulation and engage the conductive portion of the wires.
There are several known tools available for preparing the electrical cable for use in electrical receptacles as described herein by slitting and spreading such cable. One such tool is disclosed in U.S. Pat. No. 4,025,998 issued to Eppler on May 31, 1977 and assigned to the same assignee as is the present invention. The tool comprises a slitting assembly vertically slidably coupled to a cradling means and including a fixed upper jaw housing the slitting assembly and a movable lower jaw supporting the cradling means. The lower jaw is arranged to be linearly driven toward the upper jaw upon closure of pivotally coupled elongate handle members.
Another tool is shown in U.S. Pat. No. 3,846,894 issued to Parsons et al. on Nov. 17, 1974. This tool utilizes a pair of exposed slicing blades which are affixed to a blade support integrally formed on one of two elongate actuating arms. The blades are directly pivotally moved to a slicing and spreading position upon manually bringing the actuating arms toward each other.
In both these devices the principle of operation for the desired slitting and spreading effects is a steep wedging action. In achieving these effects, in particular the spreading action, there is a considerable amount of surface contact and hence a relatively high force is required to accomplish the slicing and spreading operation. The long handles are used for their mechanical advantage in generating the necessary operating forces. Such long handles disadvantageously limit the use of these tools to readily accessible areas. Also, with this method of blade engagement and force application, once the cable is slit and spread, it remains on the blades and must be forcibly removed therefrom. This removal not only increases the cost of the operation but also, in the absence of suitable instructions, increases the potential for injury where the removal is effected by hand.